Pouch packages are traditionally formed on standard form/fill/seal machines, such as model IM, made by Klockner-Bartelt of Sarasota, Fla. In such machines a continuous web or webs of material are fed to a sealing station where a typically rectangular pouch is progressively formed and closed on three sides. An open side is then filled with a measured quantity of flowable material. In a downstream station, the open side is sealed closed, followed by an operation to separate individual pouches from the continuous web or webs. Form/fill/seal machines may be intermittent motion or continuous motion machines. They provide high productivity for manufacturing inexpensive small packages.
Most packages formed on form/fill/seal machines contain fluids which are intended to be squeezed out of a torn off corner or a tear in the pouch. A common example is the ketchup package provided with an order of fries from the local burger stand. The pouch has only a single use before it is discarded.
More recently, pouch packages have been designed for reclosability so that this inexpensive, minimal material package construction may be applied to products requiring the dispensing of multiple doses of fluid from the same package. To achieve reclosability, fitments have either been formed in the pouch or bonded to the pouch for threaded or other frictional type closures, which can be removed and then reinstalled. For example, U.S. Pat. No. 4,394,936 to Shavit, dated Jul. 26, 1983, shows a cardboard tube package and a method for forming, filling, and sealing it such that a threaded fitment is sealed into a folded end of the package.
A pouch made from rectangular stock or a web or webs having parallel edges is distorted by having a fitment installed at one end. That is, the fitment has a dimensional thickness at one end of the rectangular pouch, whereas the other end is sealed flat. The flat end tends to be wider than the fitment end. Shavit provides creases in his cardboard pouch at the end opposite the fitment in order to narrow the opposite end to the same width as the fitment end. Thus, his finished package retains a rectangular shape.
In a form/fill/seal machine such as shown by Shavit, it is necessary to maintain the side seals parallel between the opposing pouch ends so that a continuous web or webs may be directed in a straight line through the machine. If one end of a pouch were wider than the other, the line of pouches progressively formed, filled, and sealed would curve in the direction of the narrower end. Pouches made of easily deformable plastic film cannot be readily creased such as Shavit's cardboard pouch. Instead, either wrinkling occurs, which interferes with sealing, or side seals cannot be maintained parallel.
The drawings of Shavit illustrate another problem associated with pouches having fitments at one end. The fitment end of the pouch is shaped in a concave manner to facilitate the thickness of the fitment in the center while being flattened at the side seals. Shavit specifies a fitment flange which is flexible in order to assume the concave shape of the pouch. A disadvantage of the concave pouch end is that it recesses the fitment relative to the perimeter of the pouch. That is, the dispensing end of the fitment is guarded by the outermost comers of the pouch side seals. When product is dispensed from the fitment, the side seal comers often interfere with the targeting of the product. A longer and more expensive fitment may be needed as a result.
What is needed is a pouch with minimal concavity at the fitment end, and a solution to the form/fill/seal machining problem of maintaining parallel side seals in pouches with fitments.